1. The present invention relates to an apparatus for X-ray photography of the area of the dentition and of the jaws, and of the type comprising a stationary frame part, a bearing part which is movably mounted to the frame part and preferably performs a linear movement, and a support arm which is rotatably attached using bearings to the bearing part and has at one end a source of X-ray radiation and at the opposite end a movable X-ray film, the movements of the bearing part, the support arm and the film being synchronized in such a way that a sharp image of only an area of the desired shape is obtained on the film, for example the area of the patient's dental arch.
2. Description of the Prior Art
In panoramic X-ray photography it is known, in order to obtain a sharp image of the dental arch, to allow the rotational axis of the support arm to move during the exposure in a predetermined manner linearly or non-linearly in such a way that this movement is dependent on the angular position of the support arm at each given time. The movement of the rotational axis may be linear, and parallel to the axis of symmetry of the dental arch, perpendicular to it, curved, or non-continous between predetermined points. The enlargement can be adjusted by shifting the location of the patient, i.e. the head-supporting devices, in relation to the support arm.
In spite of the above-mentioned movement combinations and adjustments, the image obtained is not always as sharp as would be desired, especially when some specific part of the dental arch is concerned. It is evident that it is not always possible by means of adjustments to compensate for the variation is the dentition among defferent patients. For example, a situation in which the axis of the rotational movement of the support arm is vertical and the position of at least some of the teeth deviates from the vertical, causes certain blur in the image.